IB-Flows：用于流固耦合的开源多GPU浸没边界代码

中文摘要 AI 辅助

我们介绍了IB-Flows，一个用于不可压缩流固耦合（FSI）问题直接数值模拟的开源多GPU求解器。该代码将交错笛卡尔网格上的二阶有限差分分数步Navier-Stokes求解器与两种浸没边界方法相结合：一种基于移动最小二乘（MLS）插值的拉格朗日方法和一种欧拉锐利界面方法。刚体通过基于四元数的牛顿-欧拉求解器推进，而嵌入三维流动中的可变形表面则由基于相互作用势的结构求解器描述；预测-校正方案提供松散或强流固耦合。具有剪切变稀或剪切增稠流变性的非牛顿流体通过依赖于应变率的粘度处理，同一框架还容纳了用于湍流大涡模拟的亚格子涡粘模型。该求解器使用CUDA Fortran编写，并采用MPI域分解，因此流体、插值和结构内核均在GPU上执行，而泊松和隐式求解器所需的分布式转置则通过cuDecomp库利用GPU感知通信进一步加速。强扩展和弱扩展测试显示近理想的节点内扩展和良好的多节点效率。该求解器针对一系列基准问题进行了验证，涵盖壁面湍流、刚体和可变形体流固耦合以及生物医学应用。IB-Flows旨在作为现代GPU集群上浸没边界FSI模拟的可复现参考实现，以及用于解决多物理场问题的透明平台。

英文摘要

We present IB-Flows, an open-source, multi-GPU solver for the direct numerical simulation of incompressible fluid-structure interaction (FSI) problems. The code couples a second-order finite-difference fractional-step Navier-Stokes solver on a staggered Cartesian grid with two immersed boundary methods: a Lagrangian method based on moving least-squares (MLS) interpolation and an Eulerian sharp-interface method. Rigid bodies are advanced with a quaternion-based Newton-Euler solver, while deformable surfaces embedded in three-dimensional flows are described by a structural solver based on the interaction potentials; a predictor-corrector scheme provides either loose or strong fluid-structure coupling. Non-Newtonian fluids with shear-thinning or shear-thickening rheology are handled through a strain-rate-dependent viscosity, and the same framework accommodates subgrid-scale eddy-viscosity models for large-eddy simulations of turbulent flows. The solver is written in CUDA Fortran with MPI domain decomposition, so that the fluid, interpolation and structural kernels are all executed on the GPUs, while the distributed transposes required by the Poisson and implicit solvers are further accelerated by the cuDecomp library through GPU-aware communication. Strong- and weak-scaling tests show near-ideal intra-node scaling and good multi-node efficiency. The solver is validated against a set of benchmark problems spanning wall-bounded turbulence, rigid-body and deformable-body fluid-structure interaction, and a biomedical application. IB-Flows is intended as a reproducible reference implementation for immersed boundary FSI simulations on modern GPU clusters and as a transparent platform to be used for tackling multiphysics problems.

发表机构

• Gran Sasso Science Institute (GSSI)（格兰萨索科学研究所）
• INFN–Laboratori Nazionali del Gran Sasso（意大利国家核物理研究所-格兰萨索国家实验室）
• Department of Physics and INFN, University of Rome, Tor Vergata（罗马托尔维加塔大学物理系及意大利国家核物理研究所）
• NVIDIA Corporation（英伟达公司）
• Physics of Fluids Group, University of Twente（特温特大学流体力学组）

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